Filter tow treatment



Dec. 3, 1968 T. c. FRITZ ET AL 3,413,698

FILTER TOW TREATMENT Filed Dec. 29, 1965 4 Sheets-Sheet 1 THEOD ORE 6.FR! TZ R/CHA RD E D YER INVENTORS A TTOR/VEYS Dec. 3, 1968 1'. c. FRITZETAL FILTER TOW TREATMENT 4 Sheets-Sheet 2 Filed Dec. 29, 1965 QQQ Qmm

THEODORE C. FRITZ RICHARD E OVER INVENTORS 7 BY 4l% gig/11 2 1 @zZZ/QuATTORNEYS Dec. 3, 1968 T. C. FRITZ ETAL FILTER TOW TREATMENT Filed Dec.29, 1965 4 Sheets-Sheet 5 THEODORE C. FRITZ RICHARD E 0 YER INVENTORS'BY m% 44% A Tram/Er;

Dec. 3, 1968 'r. c. FRITZ ETAL 3,413,693

FILTER TOW TREATMENT Filed Dec. 29, 1965 4 Sheets-Sheet 4 THE DOORS C FI?! 72 RICHARD E OVER INVENTORS A TTORIVEYS United States Patent3,413,698 FILTER TOW TREATMENT Theodore C. Fritz and Richard F. Dyer,Kingsport, Tenn,

assignors to Eastman Kodak Company, Rochester, N .Y., a corporation ofNew Jersey Continuation-impart of application Ser. No. 419,748,

Dec. 21, 1964. This application Dec. 29, 1965, Ser.

2 Claims. (Cl. 28-1) ABSTRACT OF THE DISCLOSURE An improved method andapparatus makes possible the production of tobacco smoke filters fromcontinuous fine denier multifilarnent tow. The method includes banding,pretensioning and longitudinally displacing individual filaments of thetow with respect to each other prior to applying a plasticizer with adual roll applicator arrangement, and thereafter subjecting the tow to agas jet treatment thereby uniformly distributing the plasticizer on thetow.

This application is a continuation-in-part of copending application Ser.No. 419,748, filed Dec. 21, 1964 entitled Filter Tow Treatment.

The present invention relates to a method and apparatus for themanufacture of tobacco smoke filters wherein fine denier per filamenttow is processed to produce filters which are more uniform in appearanceand performance, require less tow weight per unit of pressure drop andless plasticizer per filter than tobacco smoke filters produced byconventional methods and apparatus.

In the manufacture of tobacco smoke filters from special tows made up ofcrimped filaments of cellulose acetate and related plasticizablepolymeric materials it is customary to use various mechanical means forprocessing the filter tow. It is already widely practiced and well knownin the cigarette industry as disclosed by Crawford and Stevens, US.Patent No. 2,794,480, for example, to mechanically treat the tow in aplurality of steps which involve the filament separation of the crimpedtow, applying thereto a spray coating of plasticizer, followed byforming and compacting the tow into the desired filter shape. In morerecent disclosures, such as that of our co-workers Caines et al. in US.Patent 3,099,594, gaseous jet treatment means have been employed toobtain filament separation of the filter tow after it has been treatedwith an application of a plasticizer. Still another process formanufacturing tobacco smoke filters was described in the copendingapplication of Fritz, Ser. No. 259,852, filed Feb. 20, 1963, now PatentNo. 3,255,506, showing a mechanical roll means for obtaining improvedfilter tow separation. Although the above-mentioned prior art processessatisfactorily fulfill the requirements of many filamentary filtermanufacturing operations, especially those in which relatively largedenier per filament materials can be employed, they are not capable ofproducing a high quality fine denier per filament tobacco smoke filterwhich satisfies the present day demands of the industry for a filterhaving high tar removal capability. Such a filter can be produced by useof fine denier per filament tow and having each filament completely anduniformly separate from each other filament except, of course, at thosepoints where the filaments are bonded together by the plasticizer.Maximum tar removal efliciency is thus obtained by requiring the tobaccosmoke stream to impinge on a maximum area of filamentary material. Thisincrease in tar removal efficiency can be surprisingly accomplished by afilter having a minimum weight of material per filter element per unitof desired pressure drop.

3,413,698 Patented Dec. 3, 1968 It is often difficult, if notimpossible, to use conventional prior art processes to obtain suchcomplete and uniform separation of fine denier filaments. It is accurateto say that prior art processes have not been able to accomplish such anoperation with the uniformity and consistency necessary to produce anacceptable filter of the type described above. In referring to finedenier per filament we have reference to tows which are generallycomposed of filaments of smaller than 3 denier per filament.

The use of such fine denier per filament tows, which have a relativelylarge number of filaments per given tow cross-section, also requires thesolution of special problems to insure the uniform application of aplasticizer if the filters having the required degree of uniformhardness throughout the finished filter elements are to he obtained.Moreover, the emphasis on obtaining maximum tar rem-oval efiiciency withthe minimum weight of material per filter element requires that eachfilament be separated from each other filament throughout the body ofthe filter, except at those points where they are bonded together, toinsure that the tobacco smoke stream passing thereto can impinge on themaximum area of filamentary material. Sufiice it to say at this pointthat tobacco smoke filter elements produced by the prior known methodsdid not possess the degree of uniformity and tow separation necessary togive a more effective tobacco smoke filter for removing tar, as will beshown by the examples to follow.

We have discovered that the aforementioned difficulties have beensubstantially overcome by our invention of a specialized process andapparatus for manufacturing a high tar removal, uniform and relativelylight-weight tobacco smoke filter. Production of such a filter is madepossible by the use of a fine denier per filament plasticizable towwhich is extensively manipulated to give complete separation of thefilaments, followed by a uniformly distributed application of theplasticizer. Such a uniform filamentary structures does not cause thesmoke stream to channelize in localized areas of the filter as the smokepasses therethrough and therefore provides the necessary structuralnetwork of filamentary material to give the maximum contacting surfacefor the smoke stream.

Another important feature of our process is that our specialized tobaccosmoke filter is produced in such a standardized manner that the ultimatesmoker of a filtered cigarette will obtain a consistently uniform tastefrom each particular brand of cigarette. Furthermore, we have found themeans to produce such a filter with a minimum weight of material perfilter relative to the desired pressure drop reading and a substantiallylesser amount of plasticizer per filter than the filter presently beingmade by conventional methods.

Therefore, according to the present invention, we have discovered aprocess and apparatus for the satisfactory production of fine denier perfilament tobacco smoke filters which satisfy the demands of the tradefor a filter having high tar removal properties. In essence theinvention involves the combination of mechanical, fluid, and liquidplasticizer treatment steps of a fine denier per filament tow and theapparatus for carrying out these steps to effect substantially completeuniform separation of the filaments and an effective and uniformdistribution of plasticizer throughout the filamentary mass. Theapparatus of our invention is particularly characterized by the factthat it provides means for conveniently and effectively applying aliquid plasticizer in a highly uniform manner to the already uniformlyseparated filaments of the tow thereby obtaining in the ultimate productadequate filter hardness with a minimum amount of plasticizer.Furthermore, the substantial current interest in the selective removalof certain components of tobacco smoke also makes it desirable that anyimproved process or apparatus be readily adaptable to the inclusion of astep in which particulate additive such as activated carbon, sodiumbicarbonate, cellulose acetate fioc and other solid particulatematerials having selective removal properties may be added to the tow asit is being processed prior to the step of filter element formation. Ourprocess and apparatus lends itself especially well to a furthermodification of the invention in which solid particulate additives maybe added to the tow desired.

The subject matter which is regarded as our invention is clearly pointedout and distinctly claimed in the coneluding portion of thespecification. The invention, however, as to its organization andoperation together with the further objects and advantages thereof willbest be understood by reference to the following description taken inconnection with the accompanying drawings, in which:

FIG. 1 is a schematic side elevation view of an apparatus for carryingout the process of the invention.

FIG. 2 is an elevation view of a twin plasticizer applicator assembly ofour invention viewed from the plane designated by line 22 of FIGURE 1and looking in the direction indicated by the arrows.

FIG. 3 is a side elevation view of an apparatus adapted for carryingthat modification of our process in which an applicator forincorporating a particulate additive into the plasticizer treated tow isprovided.

FIGS. 4, 5, 6 and 7 are illustrations of the filament distribution inportions of the tow treated according to the various prior artprocedures.

FIG. 8 is an illustration of a filament distribution in a portion of thetow prepared by employing the process and apparatus of the invention andillustrating the high degree of filament separation and uniformity ofthe filament separation attainable by our invention.

Referring now to FIGURE 1 which is a diagrammatic overall viewillustrating the manner in which tow is processed in accordance with ourone embodiment of our invention, a continuous, fine denier per filament,e.g., 3 denier per filament or smaller, crimped, multifilament tow 46 iswithdrawn upwardly from supply package or bale 48 through a spreading orbanding jet 50 supplied with air through pipe 52, and thence over fixedguide 54 or alternately over a freely rotatable roll guide. Tow 40 thenpasses downwardly to a pretensioning apparatus generally indicated by 56and thence between the nip of contacting pretension rolls 58 and 60thereof. Bottom roll 58 is rotatably mounted by suitable bearing meansin fixed bracket 62 which is attached to the main frame 64 of theapparatus. Top roll 60 is rotatably mounted in suitable hearings in avertically movable bracket 66 which in turn is attached to fixed bracket62 by a leaf spring hinge 70 or other suitable means.

Top roll 60 is loaded downwardly against bottom roll 58 by means of apneumatic diaphragm plunger or a weighted plunger 72. Tow 46 passes fromthe nip of pretension rolls 58 and 60 forward to the nip of filamentseparating feed rolls 74 and 76 which are driven from a main drive shaft(not shown) supported on base 99 of a plug making machine (not shown).The tension in the tow 46 entering filament separating feed rolls 74 and76 is determined by the algebraic sum of the drag forces imposed on thetow by the concurrent and countercurrent air flow in banding jet 50, thefrictional drag force of the tow in passing over fixed guide 54 (or thefrictional bearing drag of the guide if a roller guide is used) and thedrag force generated by the frictional drag of the pretension rolls 58and 60.

The frictional drag of the pretension rolls 58 and 60 may be adjusted bymeans of the force applied to top roll 60 by the pneumatic or staticweight loading means 72. This pretension on the tow entering thefilament separating feed rolls 74 and 76 should preferably be kept atthe minimum sufiicient to remove secondary crimps or folds in the towWithout substantially straightenin out the primary or fine crimps in theindividual filaments. This roll pair 74 and 76 is mounted in much thesame way as roll pair 58 and 60, that is, bottom roll 74 is rotatablymounted in suitable bearings which in turn are Supported in machineframework 64 of machine 99 while roll 76 is freely rotatable in hearingsin bracket 76A. Bottom roll 74 is positively driven by a connection (notshown) to the main drive of machine 99 and drives roll 76 by frictionalcontact therewith.

In accordance with the invention top roll 76 has a configured surface,e.g., a surface with a plurality of circumferential square-formcross-section grooves and lands. Alternatively these grooves and landsmay be interrupted at intervals around the circumference of the roll.When top roll 76 is loaded pneumatically by means of air diaphragm 78 itis pressed against bottom roll 74 which preferably has a resilient,smooth surface constructed, for example, of rubber with a hardness ofabout -80 as measured by the Shore A Durometer.

Portions of tow which are passed between the nip of the lands on toproll 76 and the smooth surface of bottom roll 74 are pullled against thetension generated by roll pair 58 and and are also displaced forwardlyby a small increment relative to adjacent other portions of the towwhich are incompletely or not at all gripped in the nip of rolls 74 and76 where the grooves occur in roll 76. Thus the filaments in portions ofthe tow are longitudinally incrementally displaced relative to thefilaments in adjacent portions of the tow with the result that thefilaments are individually separated longitudinally one from the other.Stated in another manner, the pretensioned tow had been subjected to amechanical lengthwise separating action by means of the action of rolls74 and 76.

If the grooves and lands are continuous around the roll 76, the towemerging therefrom takes on the appearance shown in FIG. 5. If thegrooves and lands are discontinuous the tow will have the appearanceshown in FIG. 6. In both these figures it will be apparent that thedensity or number of filaments per unit area is variable across thewidth of the tow band due to the action of rolls 74 and 76. Thus a rollhaving continuous grooves will impart a continuous lengthwise ribbed orcorduroy effect to the tow as shown in FIG. 5, while a roll havinginterrupted lands and grooves will impart an elongated checkerboardpattern as shown in FIG. 6. Both figures are reproductions of aphotomicrograph of a portion of the tow at a magnification of about 20.Thus, though both types of rolls separate and open the filaments, theaction may be incomplete or non-uniform. In other words, where a tobaccosmoke filter is produced from a tow in which such incomplete ornon-uniform filament separation is present smoke passing therethroughmay tend to channel through zones of lesser filament density and theoverall effectiveness of the filter may thus be substantially impairedfor certain tobacco smoke filter applications, although such channelingmay not be objectionable in others. This channeling would beparticularly detrimental since it would produce filters having lowerpressure drop per unit weight of tow and, therefore, lower tar removalcapabilities.

In producing filters by use of plain rolls in conjunction with air jetssuch as is described in US. patents to Caines et al., 3,099,594, andDyer et al., 3,079,663, it has been found that certain of the filamentsmay not separate completely one from another, especially when using finedenier filament tow, e.g., 1.0 to 3.0 denier per filament tows are beingprocessed in accordance with such known processes. Thus carefulexamination of a filter tip made from fine denier tow by use of air jetsand plain rolls to separate to filaments may reveal the presence ofoccasional clusters of 2 t0 5 or more filaments that have not separatedfrom each other. Filters made from such processes tend to containclusters of unseparated filaments as illustrated in FIGS 4 and 7. FIG. 4shows a portion of a banded tow containing such clusters while FIG. 7shows the presence of such clusters in a finished filter which has beenbroken open. It is this type of non-uniformity of fiber separation whichis present in the finished filter when using prior known methods fortreating filter tow. The filter product made by our invention, asdescribed herein, results in a filter having the filamentary structuraluniformity necessary to obtain an improved and more effective tarremoval performance.

After leaving the filament separating feed rolls 74 and 76 the openedtow is passed through a pneumatic spreading or banding jet 80 which issimilar in construction and operation to banding jet 50. The action ofthis jet is further to increase the width of the band of tow and also tocontrol and maintain its width just prior to application of plasticizerto the tow by its passage through plasticizer applicator 81.

Referring to FIGURE 1, tow 46, after being subjected to the differentialpulling action of rolls 74 and 76 as it passes from pretension or dragrolls 58 and 60 and being further banded or spread out to a constantuniform width by passing through pneumatic banding jet 80, is advancedto plasticizer applicator rolls 82 and 84 which are in geared relationto each other and driven by positive means from the main drive (notshown) supported on base 99 of a plug making machine (not shown). Thefunction of these rolls is to transfer a film of liquid plasticizer toboth surfaces of the band of tow as it passes between the rolls. Theplasticizer employed in a given case will be any suitable liquidplasticizer capable of plasticizing the material of Which the filamentsof the tow are composed. For example, if the filaments are composed ofcellulose acetate, triacetin would be a suitable plasticizing agent.

As shown in FIGS. 1 and 2, rolls 82 and 84 are slidably mounted withinholder frame 90. Each roll is supplied with plasticizer by verticallydisposed dual applicators 86 and 88 which are provided with internalliquid plasticizer reservoirs 86A and 88A, respectively. Applicator 86carries wick element 86B connected to the plasticizer reservoir thereofas shown. Likewise, applicator 88 carries wick element 88B which issimilarly connected to its own internal reservoir. Reservoir 86A andwick 86B of applicator 86 are supplied through conduit 93 with a meteredamount of plasticizer by means of a metering pump (not shown). Reservoir88A of applicator 88 and its wick 88B are similarly supplied withplasticizer by means of a separate metering pump and conduit 95.

As shown in FIGS. 1 and 2, wick applicators 86 and 88 are attached,respectively, to positioning means 94 and 92, which may take the form ofsolenoids or air cylinders which may be actuated in known manner to moveapplicators 86 and 88 toward or away from rolls 82 and 84 as desired.The lengths of the respective roll contacting surfaces of wicks 86B and88B are substantially equal to the width of the outlet orifice ofbanding jet 80 and thus equal to the width of the banded tow passingbetween rolls 82 and 84.

In operation plasticizer deposited by wicks 86B and 88B on rolls 82 and84 is picked up by the tow as it passes between the rolls and a film ofliquid plasticizer is thus uniformly spread over both surfaces of thetow and into contact with all of the filamentary material of the towband.

The action of the plasticizer on the individual filaments is to softenor partially solvate the materials of which they are composed, thusrendering them capable of bonding themselves one to another at randompoints of contact throughout the filamentary mass by coalescence orfusing together of the contacting softened or partially solvatedfilament material to form a filamentary network. If solid particulatematerials such as activated carbon, sodium bicarbonate, rice starch,cellulose acetate fioc, or other additives are placed on the tow toincrease the effectiveness of the filter in removing gaseous or solidcomponents from tobacco smoke, in accordance with that embodiment of ourinvention shown in FIG. 3, these particles are effectively entrapped andfirmly held within the resulting filamentary network.

In accordance with the first mentioned embodiment of the invention, thetow, after passing through the nip of applicator rolls 82 and 84, isforwarded to venturi air jet 96 which may be of the general constructionand opera tion described in US. Patents Caines et al. 3,099,594 and Dyeret al. 3,081,951. The function of this jet is further to open the tow bycompletely separating the filaments thereof one from another and toinsure uniformity of filament separation by evening out anyirregularities in filament distribution which may have resulted from theaction of rolls 74 and 76. The action of this jet also serves theimportant added function of more uniformly distributing the plasticizerthroughout the separated filaments of the tow.

The tow will then have a filament distribution pattern similar to thatillustrated in FIG. 8 which is a reproduction of a photomicrograph of aportion of the tow at a magnification of about 20. It can be seen thatthe product has achieved a complete and uniform filament separationwhich had not been previously possible when using the methods of theprior art. For example, if we were to compare this product asillustrated in FIGURE 8 with the product of FIGURE 4, which is aphotomicrograph of a portion of tow as produced by the known method,whereby a 3 denier per filament or less tow is first carried betweensmooth surfaced feed rolls, treated with plasticizer and then bloomed ina venturi type jet, it will be seen that there is a complete absence ofclusters of unseparated filaments in the product of FIGURE 8 as comparedto the product of FIGURE 4. A significant comparison can also be madewith the product of FIG- URE 7 which is an illustration of a filter, thepaper wrap having been broken open to expose the filaments. This productwas made by a process employing jet filament separation with an S wrapwiping-type plasticizer applicator of the type disclosed in Us. Patent3,099,594. Caines et al. also shows the presence of unseparatedfilaments. These clusters or accumulations of unseparated filamentsclearly reduce the effectiveness of the finished filter and is one ofthe major disadvantages of tobacco smoke filters presently beingproduced by any of the known methods. This disadvantage is substantiallyeliminated by the process and apparatus which has been described herein.

In FIG. 3 there is illustrated that embodiment of our invention whichincludes the step of depositing solid particulate material on the towprior to actual filter formation. In this modification, the tow isprocessed by the identical steps employed in processing the tow inaccordance with the first modification of the invention as described indetail above up to the point where the tow emerges from plasticizerapplicator rolls 82 and 84. The tow may then be passed through a bandingjet 104 which serves to further separate the filaments and enhance theuniformity of their separation as well as evenly distribute theplasticizer. The tow is then carried between the pinch of freelyrotating guide rolls 106 and 107 and beneath vibratory distributor 108which deposits on the surface of the moving tow a predetermined amountof a particulate additive material such as activated carbon, sodiumbicarbonate, rice starch, cellulose acetate fioc, or other solidparticulate material which serve to enhance the ability of the ultimatefilter product to remove tars and other solid and gaseous componentsfrom tobacco smoke. The tow bearing the particulate material then'passes to a forming funnel 110 which causes it to. assume a substantialcylindrical shape, thus locking the particulate material within thefilamentary mass. The tow then passes between the pinch of deliveryrolls 112 and 114, thence into garniture 102 of a filter making machinewhere it is wrapped in a paper wrap to form the finished filter plug. Itwill, of course, be understood that the action of the plasticizerdeposited on the tow from rolls S2 and 84 7 will be as described above,that is, the material of the filaments at random points of contact willbe solvated and caused to coalesce, thus bonding the filaments togetherat these points of contact to form an open fila- 8 It was surprising toalso note that although the plasticizer metering pump speed remainedconstant, 12.9% by weight plasticizer was measured as being applied tothe tow in the process of FIG. 1, while only 9.4% by weight mentarynetwork in which the solid particulate material plasticizer was measuredas being applied to the tow by is entrapped. the prior art process.

All of the driven rolls of the apparatus may be con- Thus, some 17% ofthe plasticizer delivered by the nected either directly or through eachother to the main metering pump was lost as drippage and other losseswhen drive ofthe filter plug making machine and in this manmanufacturingthe filters by the process of Sample 1. ner carefully controlledpositive speed ratios may be 10 It was further significant that thestandard deviation of established between filament separating rolls 74and 76, the pressure drop of the rods of Sample 2 as made by applicatorrolls 82 and 84, delivery rolls 98 and 100 and our process and apparatusof FIG. 1 was 0.616 as comthe tape roll (not shown) of filter forminggarniture 102. pared to 1.149 for the Sample 1 rod made by the prior Insome cases it may be desirable to insert positive variart process. Thisis significant because it shows the reable speed devices in the drivetrains between the various liability with which our method can produceconsistently roll positions so that the tow opening and delivery rolluniform filters as measured by the pressure drop. Not speeds may beadjusted to suit the requirements of a Only are we able to produce afilter having a high pressure given size and type of filter tow to meetcertain specificadrop which effectively removes tar from tobacco smoketions of weight of filter and pressure drop. For further but our processproduces filters with a uniformly and convenience, all the apparatuselements may, as shown, standardization which assures the ultimatesmoker that be mounted on common-frame 64 so that the entire unit he canexpect to receive a more uniform tasting or may be quickly set in placeon a cigarette making hi e, flavored cigarette when smoking a particularbrand of thus enabling quick conversion from production of tobacfiltercigarette. co rods to filter rods and vice versa without excessive lossThe same tow was then processed again on the same of machine time. setupin FIG. 1, except that the plasticizer metering pump In the followingexamples and description we have set pe d wa u d ab ut 40% to ab ut 43rpm. Sample forth several of the preferred embodiments of our in- 3 ofTable I gives the data of this test result. The filter vention but theyare included merely for purposes of rods Were examined hardness and q yof bond illustration and not as a limitation thereof, and found to be atleast equal to or slightly better than Exam I the prior art rods ofSample 1. It can be stated that p our process was able to achieve afilter rod which re- A 1.6 denier/filament, 48,000 total deniercellulose quired less bonding agent for a given level of filter rodacetate tow made up of oval cross section filaments was firmness orhardness. used to produce filter rods by employing a process similarFrom the foregoing and the comparative data it may to that disclosed inCaines et al US. Patent 3,099,594 be seen that the apparatus and processof this invention using jet blooming with an S wrap wiping-typeplasticizer makes possible a to 46% reduction in the pressureapplicator. The machine operating conditions employed drop standardvariation and an improved uniform apand the test results obtained aregiven under the heading pearance of rods. Since pressure drop isdirectly related of Sample 1 in Table I below. to tar removal, a similarimprovement in tar removal The same tow was then processed on theapparatus of 40 uniformity can be expected resulting in more uniform thepresent invention as described above and further iltaste and flavor incigarettes. lustrated in FIG. 1. Details of the machine setup and testresults are listed under the heading of Sample 2 in Example II Table I.

Comparison of the tow appearance after treatment The Same tow usedExampl? I Was Processed 9 indicated that the sample 1 tow containedSeveral square-grooved roll (the mechanical filament separationseparated or unbloomed filaments as shown in FIGS. 4 P Such as thatdisclosed in the Copefiding pp and 7. By contrast, the same towprocessed on the apcation of FfitZ 5611 259,352, filed 1963, paratus ofFIG. 1 of the present invention was substannow Patent No. 3,255,506using for Sample 4 (Table I) an tially free of unbloomed filaments andhad the appearance 50 interrupted square form groove roll and for Sample5 of the tow shown in FIG. 8. (Table I) a continuous grooved roll.Machine set-up and TABLE I Sample No l 2 3 4 5 D/F 1.6 1.6 1.5 1.6 1.1;Total denier 48, 000 48, 000 48, 000 48, 000 48, 000 Filament crosssection. Round Round Round Round Round Filter length, mm 102 102 102 102102 Filter circumference, n1m 24. 83 24. 85 24.88 24. 82 24. S2Plasticized rod weight, grams:

Average .827 .875 .853 764 .805 Standard deviation 019 .021 020 008 .016Rod pressure drop:

Inches of \iater, average 18.1 18. 0 18. 2 14. 16. 1 Standarddeviation 1. 149 0. 616 0. 725 0. 332 0. 617 Hardness, 0.1 mm.penetration:

Average 7. l 6. 2 6. 5 13. 6 9. 0 Range 4. 8-9. 7 4 7-7.9 5.5-7. 4 115-15. 5 7 8-10. 5 Percent Plastieizer (Triacetin) 9. 4 12. 9 7.9 7. 3 7.0 Tow per rod, grams 681 694 709 634 .685 Inches pressure drop per gramof tow 26. 7 26. 1 25 7 23. 4 23. 5 Tar removal 57 57 58 50 53 Speedratios:

Feed 74/76 to delivery 98/100 1. 39 1. 1. 62 1. 70 1, 31 Feed 74/76 totape 01102"- 1. 22 1. 33 1. 33 1. 64 1.24 Feed 74/76 to tension 1.451.55 1.56 2.35 1. Feed 74/76 to applicator s 84 1.24 1.21 llasticizerpump, r.p.m 72 72 43 filter rod test data are listed in Table I underthe appropriate sample number headings.

Visual examination of the bloomed tow of Samples 4 and 5 clearlyindicate a less uniform separation and distribution of the filaments(FIG. 6 and 5 respectively) than for the tow of FIG. 8 treated by usingthe process and apparatus of this invention (Samples 2 and 3 in Table1).

Examination of the data shows clearly that a lower pressure drop and alower tar removal count were obtained for the Samples 4 and 5 asproduced by the prior art method of mechanical filament separation whencompared to Samples 2 and 3 as made by our invention. It was furthernoted that the tow was used less efiectively by the prior art processsince Samples 4 and 5 indicate they have only 23.4 and 23.5 inches ofpressure drop per gram of tow, respectively, as compared to 26.1 and25.7 inches pressure drop per gram of tow for the filter made by ourinvention, It was further noted that the filter rod hardness wascompletely unacceptable as required by the trade and that to improve thehardness to an acceptable level considerably more plasticizer or moretow would be necessary. This is economically undesirable.

While it was noted that the uniformity of the interrupted groove rollprocess Sample 4 was good, this uniformity occured at the cost of lowertar removal count, poorer tow utilization and loss of rod hardness.

While the process and apparatus of our invention has been compared using1.6 denier per filament oval or substantially circular section celluloseacetate tow, similar results may be obtained when non-circular crosssection filament tows with larger or smaller filament sizes and tows ofdifferent compositions such as polyolefin, polyamide, polyester or thelike are used.

It will be apparent from the above description that our invention hasresulted in certain advantages which could not have been achieved by aconventional process and/ or apparatus. We have contributed to thetechnical advance of our industry by developing a process and apparatuswhich will produce a better, more economical and more uniform tobaccosmoke filter. One such feature of our invention is the manufacture of atobacco smoke filter which is comprised of a plasticized fine denier perfilament tow which is structurally unique as characterized by itscomplete and uniform filament separation to give no evidence of filamentconglomeration. This is a result not heretofore attainable by prior artprocesses.

Our invention has the additional advantage of manufacturing filters ofthe type herein described having consistently high tar removalproperties. This has been indicated by our comparative data showing thesignificance of its low standard deviation number. Since pressure drop,uniformity of filament structure and taste of the cigarette to thesmoker are all interrelated, it can be readily seen the advantage whichresults from being able to produce a consistently standardized tobaccosmoke filter.

Furthermore, the process lends itself to being easily adaptable to theaddition of particulate material within the filter for the moreselective removal of certain components of tobacco smoke when it isdesirable to do so.

Another outstanding advantage provided by our invention is that byapplying the plasticizer to the filamentary material of the tow bydepositing the plasticizer from duplex applicator rolls, which conveysit simultaneously to both surfaces of the banded tow, much more uniformdistribution of plasticizer is obtained than was possible with prior artmethods which involve spraying particles of plasticizer onto the tow orwiping plasticizer onto the tow surfaces. Particulate sprays, forexample, tend to form a non-uniform film of plasticizer on the filamentsand this results in what may be referred to as a spotted distributionpattern. Such a distribution pattern is unsatisfactory because oneportion of the filamentary mass may receive an excess amount ofplasticizer while adjacent areas may receive none at all. When employingthe prior art wiping method, one segment of the filamentary tow mass maywipe the applicator clean while a segment immediately following mayreceive no plasticizer at all, thus producing a length-wise intermittentpattern of plasticizer distribution. Moreover, in employing wipingapplicators of the prior art, it was generally necessary to snub the towover the applicator at an angle in order to insure good contact and thiswas found to result in tensioning the tow to such extent as to removesome of the crimp from the filaments and thus reduce the ability of thetow to produce a satisfactory filter product. In other words, under suchcircumstances a greater weight of filamentary material and a greateramount of plasticizer was required to obtain a satisfactory filter ofgiven removal efiiciency. All of these undersirable occurrences areavoided by the present invention.

The process and apparatus of this invention have other unique featuresof novelty and versatility not present in porcesses and tow processingmachines of the prior art. For example, in some cases it may be desiredto produce a filter product which increases the removal of the phenolcomponent from cigarette smoke. In this case a high molecular weightpolyethylene glycol liquid additive has been found to be quite effectiveand when mixed with plasticizer can be readily applied by our improvedapparatus. However, when such a material is added to the triacetinplasticizer, the bonding power and hence the hardness of the filter rodmay be impaired. We have found, however, that by applying thepolyethylene glycol through one of the wicks of the double rollapplicator of the invention to one surface of the tow and the triacetinthrough the other wick to the opposite surface of the tow that theplasticizing action of the triacetin is not impaired and firm tobaccosmoke filter rods with a high phenol removal characteristics can thus bereadily produced.

We claim:

1. Apparatus for the production of tobacco smoke filters comprising incombination:

(a) filament separating and feed roll means for 'withdrawing a crimpedmultifilament tow from a supply package and for mechanically separatingthe filaments of said tow one from another in a lengthwise direction;

(b) pretension rolls positioned adjacent said feed roll means andadapted to nip and retard said tow being drawn therebet'ween by saidfeed roll means so that there is a straightening effect upon thefilament crimps;

(c) separate banding jet means one in juxtaposition with said supplypackage and another adjacent said feed roll means, both being adapted tospread and maintain a uniform and constant tow width;

(d) a dual roll applicator positioned adjacent said another banding jetmeans for applying a thin uniform coating of plasticzer to both spreadtow surfaces;

(e) jet treating means adapted to receive the plasticized tow and tofurther separate the tow filaments and uniformly distribute theplasticizer thereon; and

(f) delivery roll means positioned to receive and advance the tow to acigarette filter forming garniture.

2. The apparatus of 1 in which said filament separating and feed rollmeans includes at least one roll having a square-grooved surface that isadapted to coact with another roll having a resilient surface.

References Cited UNITED STATES PATENTS 3,255,506 6/1966 Fritz. 2,794,480'6/ 1957 Crawford et a1. 15-6-441 3,297,512 1/1967 Cobb et a1 156l66 XR2,774,680 12/1956 Hackney et al. a 156-299 XR PHILIP DIER, PrimaryExaminer.

